1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same, and more particularly to a metal interconnection structure of a semiconductor device having low resistance and a method of fabricating the same.
2. Description of the Related Art
Recently, the increased degree of integration of semiconductor memory devices has led to miniaturization and high densification thereof. However, such high integration enables reduction of the device size and integration of the circuits having sophisticated functions into the device and as a result, increased lengths of signal lines providing connection between the devices. Therefore, reduction of a signal line length is absolutely necessary for enhancing operating speed of integrated circuits. For this purpose, complicated circuits of the devices have been implemented by reducing the contact length and contact resistance between devices via formation of metal interconnection as a multi-layer structure.
FIG. 1 is a cross-sectional view showing a conventional metal interconnection structure of a semiconductor device.
As shown in FIG. 1, a first metal film pattern 110 is disposed on an upper part of an insulation film 105 of a semiconductor substrate 100. An intermetallic dielectric film 120 is disposed on the first metal film pattern 110. A metal contact plug 140, which is electrically connected through the intermetallic dielectric film 120 to the first metal film pattern 110, is disposed on the intermetallic dielectric film 120. A barrier layer 130 is disposed on side walls and bottom surface of the metal contact plug 140. The metal contact plug 140 is formed of a tungsten film. A second metal film pattern 150 is disposed on the upper surface of the metal contact plug 140. The second metal film pattern 150 is formed of an aluminum film.
In such metal interconnection structure of the semiconductor device, electrical connection between the first metal film pattern 110 and second metal film pattern 150 is achieved via the metal contact plug 140 composed of tungsten, as previously described. Since tungsten, constituting the metal contact plug 140, has characteristics similar to a thermal expansion coefficient of a material constituting the semiconductor substrate, for example, silicon, and is a high-melting point metal, it can be advantageously applied in the inhibition of electron detachment and a high temperature process. In addition, upon performing chemical vapor deposition (CVD), tungsten exhibits excellent step coverage and thus provides superior properties to vacuum deposition or sputtering.
However, tungsten is a material having relatively high specific resistance as compared to other metal interconnection films such as aluminum. Nonetheless, the reason why tungsten is used as the metal contact plug is that tungsten has, as mentioned above, excellent step coverage and thus is better at filling a via-hole than aluminum or copper having relatively low specific resistance. However, frequency of usage of the metal contact plug is also increased in metal interconnection structures showing a trend toward use of multi-layer structures and as a result, electrical properties of devices are gradually degraded due to a high specific resistance of tungsten.